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KrakenD Status Codes

Document updated on Oct 19, 2020

When consuming content through KrakenD, the status code returned to the client depends on the chosen configuration. Three different approaches impact status codes:

  • Use KrakenD regular endpoints to get the status codes as designed by KrakenD
  • Return the status code as provided by your backend server (see the no-op encoding)
  • Use custom logic to set specific status codes

Default status codes of KrakenD endpoints

Unless the no-op encoding is set, the following status codes are the default behavior of any KrakenD endpoint.

Status CodeWhen
200 OKAt least one backend returned a 200 or 201 status code on time. Completeness information provided by the X-Krakend-Completed header
404 Not FoundThe requested endpoint is not configured on KrakenD
400 Bad RequestClient made a malformed request, i.e. json-schema validation failed
401 UnauthorizedClient sent an invalid JWT token or its claims
403 ForbiddenThe user is allowed to use the API, but not the resource, e.g.: Insufficient JWT role, or bot detector banned it
429 Too Many RequestsThe client reached the rate limit for the endpoint
503 Service UnavailableAll clients together reached the configured global rate limit for the endpoint
500 Internal Server ErrorDefault error code, and in general, when backends return any status above 400

Why does KrakenD treat errors like a 500 Internal Server Error by default?

In most cases, when there isn’t a happy path, you’ll see KrakenD returning a 500 Internal Server Error. When KrakenD needs to combine in the final gateway response, there is no way to properly distinguish the status code from the backend and the one from the gateway itself. That’s why all errors external to KrakenD are translated into a 500 Internal Server Error.

To offer a gracefully degraded service when some backends fail, we leave the decision to the client on what to do by adding the header X-Krakend-Completed: false (some backends succeeded, others don’t) and also by adding the detailed errors feature.

Returning the status codes of the backend

If what you need is returning the content of a backend service as is, then the no-op encoding will proxy the client call to the backend service without any manipulation. When the backend produces the response, it’s passed back to the client, preserving its form: body, headers, status codes, and such.

An exception to this behavior is 30x responses, which will be followed by the gateway even with no-op encoding. If your backend returns a 301 the client won’t follow it, but the gateway.

Returning other status codes

Default status codes can be overridden per endpoint, following different implementations.

  • Using no-operation: When your call is not idempotent (i.e., a write operation), and you want the client to receive whatever the backend is responding.
  • Using a Lua script: To write in the configuration any logic, you need to evaluate and return a custom_error, with any status code of your choice.
  • As custom_error will end the pipe execution. If you just want to alter the status code, you can (in a no-op pipe) use the statusCode dynamic helper on the response.
  • Injecting your own HTTPStatusHandler

Unresolved issues?

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